Respective prevalence of the different carpentier classes of mitral regurgitation: a stepping stone for future therapeutic research and development.

Objectives: To determine the prevalence of mitral regurgitation (MR) in the U.S. adult population by classifying its mechanisms according to Carpentier's functional class.

Background: MR is the most common clinically recognizable valvular heart condition in the U.S. affecting 2 to 2.5 million people in 2000. A true estimate of the prevalence of MR in accordance to the functional class and etiology is unavailable.

Methods: We conducted a Medline search regarding prevalence and etiologies of MR. Etiologies were grouped by Carpentier's functional classification, and estimated prevalence numbers were projected to U.S. adult population of 200 million. Moderate-to-severe grades of MR were included.

Results: Carpentier type I, including congenital MR and endocarditis, has a prevalence of less than 20 per million. Myxomatous infiltration leading to mitral valve prolapse is the largest group associated with a type II mechanism with 15,000 per million prevalence. Type IIIa includes rheumatic heart disease, systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), and rare infiltrative and tropical disorders. SLE and APS have a mean prevalence of 10,520 per million. Carpentier IIIb is the largest group leading to MR, which is mostly functional, and includes ischemic cardiomyopathy, left ventricular (LV) dysfunction, and dilated cardiomyopathies. The estimated prevalence of MR in ischemic cardiomyopathy is 7500 to 9000 per million, and in LV dysfunction, 16,250 per million.

Conclusions: The largest number of people with MR is in type IIIb. Certain etiologies show overlap within functional classes due to multiple mechanisms of MR. We attempted to classify etiologies of MR by a functional class to determine the disease burden.